1. Field of the Invention
The invention relates to a press-fit type connector terminal to be inserted into an electrically conductive through-hole formed through a printed circuit board.
2. Description of the Related Art
Various press-fit type connector terminals have been suggested. For instance, there is a terminal contact section having a needle-eye, C-shaped, N-shaped or Σ-shaped cross-section.
Japanese Patent Application Publication No. 2004-134275 has suggested a press-fit type connection terminal including a head to which a cable is connected, and a body to be inserted into a through-hole formed through a substrate. The body is centrally formed with a hole extending in a length-wise direction thereof, and the body is formed with a plurality of slits extending from an inner wall to an outer wall of the body. The hole is filled with electrically conductive adhesive.
Japanese Patent Application Publication No. 2007-157469 has suggested a press-fit type terminal including a press-fit section, a terminal base, and a male terminal. The press-fit section includes a contact having a shape which is readily able to make contact with a through-hole, and a compression section composed of elastic material. The compression section is inserted into an opening of the contact, and the compression section exerts an elastic force on the contact such that the contact is compressed into the through-hole.
Since a maximum current which can run through the above-mentioned press-fit type connector terminal is dependent on a size of the press-fit type connector terminals, it is necessary to enlarge a size of them in order to make it possible to cause a higher amount of current to run therethrough. However, a through-hole of a printed circuit board into which a contact section of a press-fit type connector terminal is inserted has an upper limit in an inner diameter thereof in dependence on a thickness of the printed circuit board. If a through-hole were designed to have an inner diameter over the upper limit, contact defectiveness between the through-hole and a press-fit type connector terminal tends to occur, resulting in reduction in contact reliability.
Thus, for instance, Japanese Patent Application Publication No. 2005-135698 has suggested a press-fit type connector terminal including a wide terminal branched at a distal end thereof into a plurality of sub-terminals to be inserted into through-holes, in order to allow a large amount of current to run therethrough.
The conventional press-fit type connector terminals suggested in the above-mentioned Publications Nos. 2004-134275 and 2007-157469 are difficult to allow a large amount of current to run therethrough. Furthermore, since they are designed to have an outer diameter greater than an inner diameter of a through-hole of a printed circuit board, and make electrical contact with a through-hole by inserting the press-fit section having low elasticity into a through-hole, there are caused problems that a printed circuit board is whitened due to a contact pressure exerted by the press-fit section onto a through-hole, and a metal plated on an inner surface of a through-hole is peeled off. Since whitening of a printed circuit board means molecular destruction of components of which the board is composed, the molecular destruction induces not only degradation in electrical insulation of a printed circuit board and deterioration in a withstand voltage, but also an increase in a resistance of a circuit pattern.
The press-fit type connector terminal suggested in the above-mentioned Publication No. 2005-135698 is able to allow a large amount of current to run therethrough, because it has a wide terminal branched at a distal end thereof into a plurality of sub-terminals to be inserted into through-holes. However, since each of the sub-terminals to be inserted into a through-hole of a printed circuit board is needle-eye shaped, the press-fit type connector terminal cannot absorb a dimensional tolerance caused between a through-hole and each of the sub-terminals, resulting in degradation in contact reliability.